According to ICMJE, the standards of the right of authorship are: (1) participation in conceiving, designing or obtaining data, and analysis and interpretation of data; (2) writing a paper or participating in the revision of important contents; (3) agreeing to publish the final revised draft.
The author of the paper must be a person who directly participates in all or part of the main work such as topic selection, design, research, data analysis and interpretation, or writes the key content of the paper, and can be responsible for the content of the paper and can defend it. Those who have only participated in part of the work or an experiment, or provided some guidance and help for the paper, can not be listed as the author, but can thank them at the end of the article. The author's name is arranged under the heading according to the contribution to this article, regardless of the unit or position. The first author is the main person in charge of the paper.
When several authors jointly sign a work completed by * * *, the signing order should be arranged according to the contribution of each person. If more than one person contributes the same contribution, flexible expression can be adopted according to the relevant regulations of the journal. For example, Nature pointed out in its Notes to Authors that if it is really necessary to indicate that two or more authors are in the same position, they can be signed by "* * * and co-first author", or they can be identified by symbols next to their names, stating that "these authors have the same contribution to research work".